The present invention relates to a pressure control device and in particular for use in a pressure-fluid-operable brake system of an automotive vehicle.
Such pressure control devices are mounted between a master cylinder and a rear-wheel brake in a pressure-fluid-operable brake system of the automotive vehicle for the purpose of controlling brake force of the rear wheels by distributing the brake forces between the front and the rear axle deceleration-responsively and approximating an ideal distribution characteristic curve.
A pressure control device of this type is disclosed in the German published patent application No. 31 00 916 A1. In the pressure controller disclosed therein, the operating piston is acted upon by the inlet pressure by way of a spring and an intermediate piston. The communication between the pressure-fluid inlet and the intermediate piston is interrupted by an inertia member in the presence of a predefined deceleration. Starting from this point of time, the operating piston is displaced in opposition to the force of the spring, while the intermediate piston which has a larger cross-sectional surface than the operating piston maintains the position it last assumed.
A disadvantage of this known pressure control device is that the operating point of the inertia member is adversely effected by the influence of the viscosity and the flow velocity of the pressure fluid. In order to avoid such effects, it has been proposed in the British patent GB 2 106 205 A to provide a solenoid valve operated by an electric G-sensor. However, such design entails high costs.